Seam connection and method for manufacturing the seam

ABSTRACT

This application involves a method of forming spiral sheet metal seams of the type that are required between the side walls and ends of a steel drum. The seam is made in a spiral having a seal in its heart. The sheets which define the spiral are in mutual contact for the full length of at least one of them.

United States Patent Coppens et a1. 1451 June 5, 1973 54] SEAMCONNECTION AND METHOD 2,043,694 6 1936 Battles ..113 120 1. FORMANUFACTURING THE SEAM 475,656 5/1892 Bertels s ..220 79 2,078,5304/1937 Courtright v A ..l 1 3/120 L Inventors; Matheus PP s Heide-2,197,439 4 1940 Sebell ..220 67 Kalmthout. Belgium; Heinrich J.2,327,731 8/1943 McClary.... 13/120 Y Steen, Roosendaal, Netherlands2,362,846 11 1944 OBrien .113 120 Y 2,321,408 6/1943 Mills et al...113/120 Y [73] Assignee: Koninklijke Emballage lndustrie, 3,472,41710/1969 Fox ..220/67 Van Leer, N.V. 911,085 2/1909 Stollberg ....220/67190,243 5/1887 Niedrin haus.... ..220/67 [22] Flled: July 27, 19702,337,452 12 1943 compo? ..113 120 Y [21] APPL No; 58,619 2,555,7006/1951 O'Neil ..113/120Y Primary Examiner-Richard J. Herbst 1 ForeignApplication Priority Data Assistant Examiner-M. J. Keenan Aug. 1, 1969Netherlands ..6911769 Davis Moshe 52 us. 01. ..113/120 Y, 220/67 [57]ABSTRACT [51] Int. Cl. ..B2ld 51/00 This application involves a methodof forming spiral [58] Field of Search .1 13/1 E, 120 K, 120 Y, sheetmetal seams of the type that are required 113/121 A, 121 C; 220/67, 5 R,5 A, 76, 79 between the side walls and ends of a steel drum. The seam ismade in a spiral having a seal in its heart. The [56] References Citedsheets which define the spiral are in mutual contact for the full lengthof at least one of them. UNlTED STATES PATENTS 4 Claims, 11 DrawingFigures 3,586,204 6/1971 Roper ..220/67 PATENTEUJUH 5197s 3 736. 893

SHEET 1 OF 4 5 lg .1 PRIOR ART 5 lg E PRIOR ART PATENTEDJUH 5197a3.736.893

SHEET 20F 4 Fig- 3 PATENTEDJUH 5|975 3,736,893

SHEET 30F 4 Fig. 4

PATENTEDJUH 5191s 3.736.893 SHEET u or a Fig-5a 7 g 5b F: g E 7 15; 50

i ii? 12 13 PRIOR ART PRIOR ART PRIOR ART PRIOR ART SEAM CONNECTION ANDMETHOD FOR MANUFACTURING THE SEAM The present invention relates to amethod of forming a seam connecting the edges of at least two sheets of5 metal in which the edge of one of the sheets is bent about 360 or moreand to the product so formed. The state of the art respecting suchmethod and product is to be found in British Pat. No. 1,153,872 and inpublished Dutch patent application 64,06427.

Seams are produced according to the known method by rolling the sheetedges which have to be connected in a profiled seaming roller whichgives the edge of the sheet which has to form the outer layer of theseam a protruding portion with respect to the other sheet edge, theouter edge of said protruding portion being bent somewhat in thedirection of seaming before the real seaming operation is started. Asealing compound is applied during the manufacturing of the seam.

When the rolling operation is finished the sheet edges grip around eachother, but there is still however a large clearance between them. Toclose said clearance and to obtain a seam which is tight, the rolledsheet edges are rolled flat in such a way that a seam is obtained inwhich the sheet edges grip around each other by means of sharp folds.With a simple double seam as generally known at least one of the sheetedges is folded twice over 180. With the seam according to FIG. 6 of theabove-mentioned British specification at least one of the sheet edges isfolded three times over 180. The greater the number of folds the moredifficult it is to arrange the sheet edges within the seam at the properplace with respect to each other. Said edges should overlap each otheras much as possible. In practice it is difficult to locate said edges atthe proper place with respect to each other since there always aredifferences in qualities of material and thickness of the sheets whichaffect the length of the sheets to be seamed.

The flattening of the seam according to prior art practice causesincreased strain hardening at the region of the sharp folds and this hasthe effect of making the seam subject to bursting under load.Furthermore where the prior art seams are used in making metal drums,dropping of the drum has been found to cause leakage. It appears that,because the seam is more or less rectangular in section, it hasdifferent bending resistance in different directions so that deformationcaused by dropping the drum makes the seam buckle and unroll enough tocause leakage. Flattening also involves the risk of overseaming, anexpression which means that during flattening the material is pressedinwardly over the counter pressure member.

For the manufacturing of a seam it is well known to use seaming rollers.The aforementioned British specification describes a method for themanufacturing of a triple seam in which first of all by means ofa firstseaming roller the protruding sheet edge is folded back upon the othersheet edge after which by means of another seaming roller both edges arerolled into a still open spiral shape, which subsequently by means of athird roller is flattened to form the well known triple seam containingseven layers. Said seven layers can be considered to be seven cylindersfitting into each other. In general a sealing compound is injectedduring said operations said sealing compound e.g. being a rubber wateremulsion.

Said known method requires that after assembling the preshaped partsthree different seaming rollers have to engage the sheet edges tomanufacture the closed seam. This is true as well when instead of atriple seam the more usual double seam is made. The seam obtainedwhether double or triple, has the disadvantage that the cylindricalportion of the seam results into different moments of inertia withrespect to the different axis of bending since the substantiallyrectangular cross section is longer in axial direction than in radialdirection in the case of a seam of a drum. When during transportationdeformation occurs torsion is the result with the before mentionedopening of the seam.

Further it is almost impossible to obtain an air tight connection andvery often not possible to obtain a liquid tight connection with doubleseams and triple seams as well. The sealing compound which during theseaming operation is injected is spread at random between the layers ofthe sheets due to the seaming operation and accordingly does not form acoherent layer which layer furthermore loses volume by drying so thatsmall openings are formed. In case one applies the sealing compoundprior to the seaming operation to avoid said disadvantage the sheetedges which during the seaming operations shift over each other will cutthe sealing compound, displace it by shifting it and will scratch itinto pieces.

It is observed that attempts have been made to manufacture a round seam.To this end, however, first of all the sheet edges were welded togetherand subsequently bent into an open roll.

It is therefore an object of the present invention to provide a seamwhich is free of the defects of prior art constructions.

It is a further purpose of the invention to provide a method by means ofwhich it is possible to manufacture the seam according to the inventionwithout the objections inherent in the known methods of manufacturingseams.

According to the invention this is achieved by first of all bending theaforementioned outer edge by means of a separate seaming roller toconform to a very small radius over about without touching or preventingthe assembly of it with the other sheet edge. After this, a sealingmeans or compound is applied in the hollow space thus formed andconditioned. Then both sheet edges are closely rolled upon each otherinto a closed spiral shaped cross section by means of one single seamingroller. Thus primarily the sheet edge of the protruding portion isformed with a hollow or channellike portion in which the sealing meansare applied. This bent portion has such a small radius that it forms thecore for the further folding or rolling operation. It is filled withsealing means. During the further seaming operation said other edge iscored in said bent hollow edge namely in the sealing compound or meanspresent in it but cannot, however, shift with respect to said edge sothat the sealing material, although being compressed and ensuring thesealing, cannot be shifted or scraped away. By the fact that the foldingor rolling takes place by means of one single seaming roller only tworollers are necessary for making the closed seam. Accordingly the numberof operations is reduced by one with the end result of a closed massiveseam with moments of inertia which are equal or at least almost equal inaxial and radial direction respectively.

In the case of connecting the flange of a cover with the flange at theedge of a drum which means the connection of sheet edges extendingperpendicularly to the axis of the cylindrical portions of cover anddrum, then in accordance with the invention it is necessary that toenable the assembly of drum and cover that the edge of the drum at thelocation of transition towards the flange is given a radius which isconsiderably larger than the radius of curvature at the location oftransition of the flange of the cover towards the cylindrical portion ofthe cover, whilst further the inner diameter of the edge of the coverbent over substantially l80 during the first operation is a little bitlarger than the outer diameter of the flange of the drum. This isnecessary to enable the placement of the cover upon the drum body afterthe application of the sealing material to the bent edge of the cover.This larger radius is necessary to enable the inner layer to be woundwith the outer layer into a closed spiral without undesirabledeformations or upsettings. These might occur if the flanges of drumbody and cover at the location of the transitions would have radii whichwould correctly fit into each other. The portions to be rolled or foldedaround each other have different arc length. With the known methoddescribed in the aforesaid British patent the cylindrical portions ofcover and drum body support upon each other during the seaming operationand accordingly the edges must shift with respect to each other whilstaccording to the method of the invention the edges cannot shift withrespect to each other so that the relative movement during the seamingoperation has to take place backwards which means in the direction ofthe cylindrical portions. In view of the fact that said cylindricalportions are not allowed to shift, with respect to each other the spacerequired is obtained by means of the larger radius.

Thus, according to the present invention the sheet edges are rolled intoa proper spiral shaped winding which is substantially closed up to itsheart. This means that when folding the sheet edges said edges areclosely rolled around each other such that at the end of the rollingoperation a seam is obtained which is almost massive, or in other wordswithout any clearance between the sheet edges, and which can no longerbe flattened and need not to be flattened. The earlier mentionedtolerances are of no importance any more since the quantity of materialto be folded is equal to the quantity in the closely rolled finishedseam. By the fact that said seam has a proper spiral shape its heightand width are almost equal to each other. If the seam is used forconnecting a wall and bottom of a container such as a drum, this meansthat at least in radial direction the present invention has a largermoment of inertia of the seam as compared with the known seam startingfrom the same quantity of material and accordingly this invention has alarger strength in that direction where it is desired most. I

Seams according to the present invention have virtually equal bendingresistance in all directions, are leak resistant and yet may be madewith fewer steps and less material than prior art processes.

According to the invention it is preferred that the sealing means arebrought in the final condition before the seaming operation is done.This means that in case a liquid is applied said liquid first has to bedried to obtain a closed, well adhering film. It is also possible toapply a loose ring of synthetic resin or rubber which fits into thehollow space. According to the invention the use of polyurethane sprayedinto the hollow space and allowed to set is preferred.

I The invention now will be further elucidated with reference to thedrawings.

FIG. 1 shows a prior art seam in cross section after the seamingoperation and before the flattening operation.

FIG. 2 is a cross section through the seam of FIG. 1 in its finishedflattened form.

FIG. 3 is a cross section through a seam according to the invention.

FIG. 4 shows a different embodiment of the seam according to theinvention.

FIG. 5a to d inclusive show schematically the manufacturing of a tripleseam according to the method known from British specification No.1,153,872.

FIG. 6 shows the form of the cover according to the invention.

FIG. 7 shows the same cover after bending the edge over FIG. 8 showsdiagrammatically the situation of the portions to be connected beforethe seaming operation starts.

FIG. 1 clearly shows how after the known rolling operation the bentsheet edges engage each other with large clearance. To close the seam toobtain the form shown in FIG. 2 a flattening operation by means of rollshas to take place. The seam is then higher than it is thick.

In FIG. 3 one embodiment of the seam according to the invention has beenshown in the form of an uninterrupted spiral shaped winding.

FIG. 4 shows another embodiment of the seam according to the inventiondiffering from the one according to FIG. 3 in that the sheet edges arerolled over a smaller angle.

Whereas according to the embodiment of FIG. 3 the outer plate 1 has beenrolled over more than 540 and the inner sheet over more than 360 in theembodiment of FIG. 4 the outer sheet 1a has been folded over a littlebit more than 450 and the inner sheet 2a over a little bit more than270.

FIG. 3 and FIG. 4 respectively show a cover 1 and la respectively and aside wall 2 and 2a respectively of a drum and said two parts areconnected with each other by means of the seam 3 having the form of aclosed spiral shaped winding. Since the example shown shows a circularseam the sheet edges during the seaming operation have to be deformedtowards a smaller diameter which causes an increase of the metal sheetthickness. This happens with each seam and accordingly also with theseam according to the invention. This thickness increase, however,promotes the filling of the seam center whereas it has no particularadvantage for flattened seams.

Whereas for the manufacturing of the known seam a seaming roller is usedhaving a groove the diameter of which being such that an open almostspiral shaped winding is formed which can be flattened, it is necessaryfor the manufacturing of the spiral shaped winding according to theinvention to use a seaming roller the groove of which having dimensionsof which height and depth correspond to the dimensions h and d shown inFIG. of the drawings.

FIG. 5a to d inclusive relate to the manufacturing of the prior art seamby the prior art process.

FIG. 5a shows a cover 5 with flange 6 and protruding portion 7 as wellas a drum body 9 with flange 10.

FIG. 5b shows how by means of a first rolling operation with the roller1 1 the protruding portion 7 is folded back upon the flange 10.

FIG. 5c shows how by means ofa further roller 12 the seaming operationis performed during which the flange 6 is turned three times so that incross section seven layers are formed which seam, however, is notclosed.

FIG. 5d shows how by means of the roller 13 the open seam of FIG. 50 isclosed by flattening to produce an almost rectangular seam as viewed incross section.

The final form obtained is similar to the one shown in FIG. 2.

During said flattening operation it is in practice very difficult toproperly define the degree of flattening. The tolerance in platethickness and hardness and the degree of wear of the machine lead toadjusting the pressure force rather high. This, however, means thatthicker and softer sheets are compressed too much and saidover-deformation reduces the deformability of the material very often tosuch a degree that if during transportation further deformations occurthis will lead to cracks of the sheet.

For the method according to the invention one starts from a cover shapeas shown in FIG. 6, which form in principle does not deviate from theform as shown in FIG. 5a. Said cover is stamped out of a flat sheet andhas an outer edge 13 at the flange 14 which is already somewhat bentinwardly. In said area it is possible already to apply sealing materialsuch as polyurethane indicated at 15.

The next operation shown in FIG. 7 is that the edge 13 provided with thesealing material 15 or not is curved by means of the roller 16 into ahollow edge with a very small radius. If the sealing material has notbeen applied before said operation it has to be applied now and ifnecessary brought into its final condition e.g. by drying hardening,vulcanization, glueing of a rubber ring or the like.

Thereafter the cover 17 and drum 18 are assembled. FIG. 8 shows that theedge of the drum has been provided with a flange 19 the transfer areabetween flange edge and drum body having a large radius of curvature 20.The outer diameter of the flange 19 is smaller than the inner diameterof the curved edge portion 13 filled with sealing means.

By means of the roller 21 the further seaming operation takes place.This is done from the position shown in FIG. 8 by means of one singleroller 21 forming the sheet edges into a complete closed spiral whichflanges independence of their width will be rolled into each other overtwo times l80 to e.g. three times 180 the center or heart being formedby the circular cross section of the hollow edge 13 made with the aid ofthe roller 16.

The radius of the groove in the roller 21 is defined by the sheetthickness and the number of windings to be made. If the spiral windingis 2.5 times 180 the outer side of the seam in principle is circular. Ifthe winding is continued to e.g. three time 180 then the upper half ofthe seam may have a little different circular form than the lower half.The result of the last possibility has been shown in FIG. 3. FIG. 4shows a seam with a spiral shape of 2.5 times and an outer shape which,in principle, is circular.

What is claimed is:

l. A cylindrical sheet metal container of large volume includingcircumferential beads comprising a cylindrical container body having afirst flange-like sheet edge; a circular cover having a secondflange-like sheet edge; a seam connection between the first and secondsheet edges, said seam connection including said first and second sheetedges wherein said first sheet edge is bent about an angle of more than270 and said second sheet edge is bent about an angle of more than 360,as seen from the beginning of curvature of the respective first andsecond edges, and wherein said first and second sheet edges are in aspiral shaped winding of gradually changing radii and are inmetal-to-metal contact throughout the entire cross-section of said seamconnection; and a sealing compound exclusively in the center of saidseam connection, said sealing compound completely filling said centerand being under pressure.

2. A method of manufacturing a triple seam connection for a containerbetween a cylindrical body of said container and a round cover, saidbody and said cover being made of sheet metal and having, respectively,first and second flanges which extend in a radial plane with respect tothe axis of the container, said second flange forming the outer layer ofthe seam connection and having a portion which extends with respect tosaid first flange, said portion having an outer edge which is initiallybent in the general direction of sealing before a seaming roll operationbegins, comprising the steps of:

a. bending said outer edge of said second flange about 180 into aU-shaped bend with a first seaming roller having in cross-section asemi-circular groove of a very small radius, said bending being donewithout folding said body and without said U- shaped bend surround saidfirst flange;

b. applying a sealing compound in the U-shaped bend;

c. forming the first flange in which a side wall of said body mergesinto said first flange with a radius which is considerably larger thanthe radius of curvature at the junction of said second flange and anadjacent cylindrical portion of said cover;

d. mounting said first and second flanges together;

and

e. rolling said first and second flanges closely into each other with aradially operating second seaming roller having, when viewed incross-section, a semi-circular groove bottom in which said second flangeis bent over more than 360 and said first flange is bent over more than270 to form a seam connection having a closed spiral shapedcrosssection.

3. The method of claim 2 in which the sealing compound is brought intoits final condition before the seam connection is made.

4. The method according to claim 3 in which the sealing compound ispolyurethane.

1. A cylindrical sheet metal container of large volume includingcircumferential beads comprising a cylindrical container body having afirst flange-like sheet edge; a circular cover having a secondflange-like sheet edge; a seam connection between the first and secondsheet edges, said seam connection including said first and second sheetedges wherein said first sheet edge is bent about an angle of more than270* and said second sheet edge is bent about an angle of more than360*, as seen from the beginning of curvature of the respective firstand second edges, and wherein said first and second sheet edges are in aspiral shaped winding of gradually changing radii and are inmetal-tometal contact throughout the entire cross-section of said seamconnection; and a sealing compound exclusively in the center of saidseam connection, said sealing compound completely filling said centerand being under pressure.
 2. A method of manufacturing a triple seamconnection for a container between a cylindrical body of said containerand a round cover, said body and said cover being made of sheet metaland having, respectively, first and second flanges which extend in aradial plane with respect to the axis of the container, said secondflange forming the outer layer of the seam connection and having aportion which extends with respect to said first flange, said portionhaving an outer edge which is initially bent in the general direction ofsealing before a seaming roll operation begins, comprising the steps of:a. bending said outEr edge of said second flange about 180* into aU-shaped bend with a first seaming roller having in cross-section asemi-circular groove of a very small radius, said bending being donewithout folding said body and without said U-shaped bend surround saidfirst flange; b. applying a sealing compound in the U-shaped bend; c.forming the first flange in which a side-wall of said body merges intosaid first flange with a radius which is considerably larger than theradius of curvature at the junction of said second flange and anadjacent cylindrical portion of said cover; d. mounting said first andsecond flanges together; and e. rolling said first and second flangesclosely into each other with a radially operating second seaming rollerhaving, when viewed in cross-section, a semi-circular groove bottom inwhich said second flange is bent over more than 360* and said firstflange is bent over more than 270* to form a seam connection having aclosed spiral shaped cross-section.
 3. The method of claim 2 in whichthe sealing compound is brought into its final condition before the seamconnection is made.
 4. The method according to claim 3 in which thesealing compound is polyurethane.